JPH07190518A - Refrigeration cycle - Google Patents

Abstract

PURPOSE:To provide a high reliability refrigeration cycle by improving compressor performance and preventing wearance and baking. CONSTITUTION:A refrigeration cycle 10 employs an HFC refrigerant or a mixture refrigerant as a compressor refrigerant in one including a compressor 11, and uses as compressor lubricating oil freezing oil that is incompatible with the refrigerant and has a larger specific gravity than the liquid refrigerant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a refrigerant for a compressor, which contains H
The present invention relates to a refrigeration cycle using FC or a mixed refrigerant thereof, and more particularly to a refrigeration cycle with improved compressor performance and improved reliability.

[0002]

2. Description of the Related Art A refrigeration cycle is incorporated in an air conditioner or a refrigerator for cooling and heating a room. The refrigeration cycle comprises a refrigerant circulation circuit in which a compressor, a condenser, an expansion mechanism such as a capillary tube, and an evaporator are sequentially connected and closed. The refrigerant used in the refrigeration cycle is C
FC (chlorofluorocarbon) 12 (hereinafter referred to as R12) or HCFC (hydrochlorofluorocarbon) 22 (hereinafter referred to as R22) is used, and R22
Refrigerating machine oil compatible with the refrigerant and the R12 refrigerant is used as the lubricating oil for the compressor. For example, mineral oil is used as the R22 refrigerant.

When a refrigerating machine oil is selected which is compatible with a refrigerant, the compressor is driven to dissolve the mineral oil in the compressor into the refrigerant, and the mineral oil is discharged from the compressor together with the refrigerant into the refrigeration cycle. Since the refrigerating machine oil discharged into the refrigeration cycle has good solubility with the refrigerant, the refrigerating machine oil is diluted with the refrigerant to reduce the oil viscosity, and is circulated in the refrigeration cycle and returned to the compressor along with the refrigerant flow.

On the other hand, recently, instead of R12 and R22 refrigerants, H that is more stable and more environmentally friendly than HCFC refrigerants in the atmosphere
FC (hydrofluorocarbon) has been developed as a refrigerant for compressors, and the same concept as that of the conventional refrigeration cycle using R12 refrigerant or R22 refrigerant is applied to the refrigeration cycle using this HFC refrigerant. HF
As a C refrigerant, for example, HCFC134a (hereinafter, R134
It is called a. ) Is adopted in the refrigeration cycle, R134a
Refrigerating machine oils such as polyalkylene glycol oil, polyol ester oil, and carbonate ester oil, which are compatible with the refrigerant, are used.

[0005]

When a refrigerating machine compressor lubricating oil for a refrigeration cycle employs a lubricating oil compatible with a refrigerant, when the refrigerant dissolves in the refrigerating machine oil, the refrigerating machine oil is diluted and the oil viscosity of the refrigerating machine oil increases. As a result, the oil sealability is deteriorated, some of the high pressure refrigerant gas compressed by the compressor leaks to the low pressure side, and there is a problem that the compressor performance deteriorates, or the refrigeration oil dissolves in the refrigerant and becomes Since it was taken out to the refrigeration cycle, the oil level inside the compressor dropped, and there was a risk of oil shortage.

Further, since the refrigerant is dissolved in the refrigerating machine oil to be diluted and the oil viscosity is lowered, the lubricity of the refrigerating machine oil is lowered and the sliding parts of the compressor may be worn. When using HCFC refrigerant in the refrigeration cycle,
Chlorine atoms present in the molecular structure dissolve in refrigerating machine oil and act as a chlorine-based extreme pressure additive to prevent wear and wear, so there is no problem, but in HFC refrigerants there are no chlorine atoms and the refrigerant is refrigerating machine oil. Since it functions only as an oil diluent, it has been a problem that the sliding parts of the compressor are worn or damaged.

Further, when the compressor incorporated in the refrigeration cycle is stopped for a long time, the phenomenon that the refrigerating machine oil and the liquid refrigerant are separated into two layers often occurs when the temperature is low such as in winter. At this time, since the liquid refrigerant is heavier than the refrigerating machine oil, it is retained in the lower layer side. If the compressor is started in this state, the oil pump attached to the motor output shaft sucks the liquid refrigerant in the lower layer and sends it to the oil lubrication part.Therefore, poor lubrication may occur, resulting in deterioration of the function such as seizure of the compressor. there were.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a highly reliable refrigeration cycle which improves compressor performance and prevents abrasion and seizure.

Another object of the present invention is to provide a refrigerating cycle in which the refrigerant is prevented from dissolving in refrigerating machine oil to prevent a decrease in oil viscosity, the oil sealability is excellent, and the compressor performance is improved.

Another object of the present invention is to provide a refrigeration cycle in which the refrigerating machine oil is prevented from being diluted so that the lubricating performance is improved and the wear and damage of the compressor are reduced.

Still another object of the present invention is to prevent the refrigerant from being dissolved in the refrigerating machine oil, to prevent the refrigerating machine oil from being taken out into the cycle, and to effectively prevent the oil level from degrading in the compressor, thereby causing oil shortage. It is to provide a refrigeration cycle that does not generate

Another object of the present invention is to make the specific gravity of the refrigerating machine oil larger than that of the liquid refrigerant to prevent the liquid refrigerant from being fed into the sliding parts of the compressor when the compressor is restarted, and to effectively prevent seizure or damage of the compressor. To provide a refrigeration cycle to prevent.

[0013]

In order to solve the above-mentioned problems, a refrigerating cycle according to the present invention is, in a refrigerating cycle including a compressor, an HFC refrigerant or a HFC refrigerant as a compressor refrigerant. The mixed refrigerant is adopted, and refrigerating machine oil that is incompatible with the refrigerant and has a larger specific gravity than the liquid refrigerant is used as the lubricating oil for the compressor.

In order to solve the above-mentioned problems, the refrigeration cycle according to the present invention is provided with an oil separator in the refrigeration cycle, as described in claim 2 in addition to the contents of claim 1. The machine oil is separated from the refrigerant for the compressor, or the refrigerating machine oil contains polyphenyl ether, silicone oil, tricresyl phosphate, triphenyl phosphate, dimethyl phthalate, chlorofluorocarbon or perfluorocarbon. A fluoroalkyl polyether or a mixed oil thereof is used, or as described in claim 4, the refrigerating machine oil is molybdenum disulfide, tungsten disulfide, graphite fluoride,
A solid lubricant additive such as polytetrafluoroethylene is added.

[0015]

The refrigerating cycle according to the present invention uses the environment-friendly HFC refrigerant or HFC mixed refrigerant as the refrigerant for the compressor, and the lubricating oil for the compressor is incompatible with the refrigerant and has a specific gravity higher than that of the liquid refrigerant. Since a large refrigerating machine oil is used, it prevents the refrigerant from dissolving in the refrigerating machine oil in advance, prevents the oil viscosity from decreasing due to dilution, improves oil sealability and compressor performance, and prevents wear and seizure. Can be prevented and a highly reliable refrigeration cycle can be provided.

Further, since the refrigerating machine oil is held incompatible with the refrigerant, it is possible to prevent the refrigerating machine oil from being diluted and to improve the lubricating performance.

Further, since the refrigerant is prevented from being dissolved in the refrigerating machine oil, it is possible to effectively prevent the refrigerating machine oil from being taken out to the refrigeration cycle, prevent the oil level from decreasing in the compressor, and prevent the occurrence of oil shortage. You can If an oil separator is provided in the refrigeration cycle, even a small amount of refrigerating machine oil discharged from the compressor can be collected by this oil separator.By guiding the collected refrigerating machine oil to the compressor suction side, The oil level becomes even more stable.

Furthermore, the refrigerating machine oil is HFC refrigeration or HF.
Since it is incompatible with C-mixed refrigerant and has a higher specific gravity than liquid refrigerant such as HFC refrigerant, refrigerating machine oil can be smoothly guided to the compressor lubrication part by the oil pump when the compressor is restarted, and seizure of the compressor And damage can be effectively prevented.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the refrigeration cycle according to the present invention will be described below with reference to the accompanying drawings.

This refrigeration cycle is incorporated in a refrigerator such as an air conditioner or a refrigerator for cooling and heating the room. FIG. 1 shows a typical example of this refrigeration cycle. The refrigeration cycle 10 includes a compressor 11, a condenser 12, and a capillary tube 1.
The expansion mechanism 14 such as 3 and the evaporator 15 are sequentially connected to form a closed refrigerant circulation circuit.

The refrigeration cycle 10 has an oil separator 16 installed on the discharge side of the compressor 11, while the compressor 1
The accumulator 17 is installed on the suction side of 1. The oil separator 16 separates the refrigerating machine oil carried out along with the refrigerant discharged from the compressor 11. The refrigerating machine oil separated by the oil separator 16 is sent to the suction side of the compressor 11, for example, the accumulator 17 through the oil return line 18. The oil separator 16 is configured as shown in FIG. Then, the retainer 21 which also functions as a partition member is housed in the closed case 20,
The discharge refrigerant discharged through the discharge pipe 22 of the compressor 11 into the expansion chamber / separator chamber 23 is given a centrifugal force by the retainer 21 and collides with the peripheral wall of the retainer 21 and the hermetically sealed case 20. Refrigerator oil is removed. The discharged refrigerant from which the refrigeration oil has been separated and removed is retained by the retainer 21.
After the pressure pulsation is suppressed from the punching hole (not shown) in the cleaner chamber 24 which also serves as the second expansion chamber, the discharge pipe 2
5 is guided to the condenser 12 side.

On the other hand, the refrigerating machine oil separated by the oil separator 16 is stored at the bottom of the closed case 20. The stored refrigerating machine oil passes through the oil port 18a at the bottom to the oil return line 1
8 and sent to the suction side of the compressor 11.

By the way, the refrigerant for the compressor circulating in the refrigeration cycle 10 is more stable in the atmosphere than the HCFC refrigerant, and is an environment-friendly HF that does not destroy the ozone layer.
A C (hydrofluorocarbon) refrigerant or an HFC mixed refrigerant is used. This HFC refrigerant contains HFC-3
2 (hereinafter, referred to as R32) and HFC-125 (hereinafter, referred to as R32)
It is called R125. ), HFC-134a (hereinafter, R13
It is called 4a. ), Etc., and as HFC mixed refrigerant, mixed refrigerant of R32 and R134a, R32 and R12
5 and R134a mixed refrigerant, R125 and HFC143a
There is a mixed refrigerant of (hereinafter referred to as R143a) and R134a.

R32 / R125 as HFC mixed refrigerant
The mixed refrigerant has a mixing ratio of weight percent (wt%).
Then, for example, R32: R125 = 60 wt% to 40 wt
%: 40 wt% to 60 wt%, and the HFC mixed refrigerant is preferably the refrigerant shown in FIG. The specific gravity of the refrigerant shown in FIG. 3 is the specific gravity of the liquid refrigerant of the HFC refrigerant and the HFC mixed refrigerant.

Further, the compressor 1 of the refrigeration cycle 10
To lubricate No. 1, refrigerating machine oil shown in the list of FIG. 3 is used. These refrigeration oils are HFC refrigerants and HFCs.
It is incompatible (not compatible) with the mixed refrigerant.
The criterion for selecting the refrigerating machine oil is one having a larger specific gravity than the HFC refrigerant or the HFC mixed refrigerant used in the refrigeration cycle 10. Compatibility refers to the property that two or more substances have an affinity for each other and, when mixed, form a solution or a homogeneous mixture.

As the refrigerating machine oil, polyphenyl ether, silicone oil, tricresyl phosphate, triphenyl phosphate, dimethyl phthalate, chlorofluorocarbon or perfluoroalkyl polyether or a mixed oil thereof is used.

Specifically, R32 (60 wt%) / R12
For a mixed refrigerant of 5 (40 wt%), as refrigerating machine oil, polyphenyl ether, phenyl-modified (epoxy-modified or fluorine-modified) silicone oil, tricresyl phosphate, triphenyl phosphate, phthalic acid Dimethyl, chlorofluorocarbon, perfluoroalkylpolyether or a mixed oil of these is selected. This refrigerating machine oil has no compatibility (incompatibility) with the refrigerant and has a larger specific gravity than the liquid refrigerant. Refrigerating machine oils are selected for other refrigerants on the same basis.

On the other hand, although a conventionally used phosphorus-based antiwear agent or the like may be used for the refrigerating machine oil, it may be considered that the refrigerating machine oil and the refrigerant have poor solubility, so that the refrigerating machine oil has a lubricating film. A solid lubricating additive may be added as an additive for the purpose of improving Solid lubricant additives include molybdenum disulfide, tungsten disulfide, graphite fluoride, polytetrafluoroethylene, and the like.

Next, the operation of the refrigeration cycle will be described.

By driving the compressor 11 of the refrigeration cycle 10, the high-temperature and high-pressure discharge refrigerant compressed by the compressor 11 is discharged to the condenser 12 through the oil separator 16. The discharged refrigerant radiates heat in the condenser 12 and is condensed to become a liquid refrigerant. The liquid refrigerant is decompressed by the expansion mechanism 14 and expanded, and then guided to the evaporator 15 where it absorbs heat and is evaporated. The refrigerant that has absorbed heat in the evaporator 15 is sufficiently gas-liquid separated by the accumulator 17,
The liquid refrigerant is removed and is returned to the compressor 11.

In the refrigerating cycle 10, since the lubricating oil (incompatible oil) which is incompatible with the HFC refrigerant or the HFC mixed refrigerant is used as the refrigerating machine oil for lubricating the compressor 11, the refrigerating machine oil which is incompatible with the refrigerant is used. Is the compressor 11
It is rarely taken out to the refrigeration cycle 10 together with the refrigerant discharged from. Therefore, it is possible to prevent the oil level of the refrigerating machine oil stored in the compressor 11 from being lowered, and it is possible to maintain sufficient lubricating performance.

However, by driving the compressor 11, a small amount of refrigerating machine oil is taken out together with the discharged refrigerant.
In this case, since the oil separator 16 is installed on the discharge side of the compressor 11, a small amount of refrigerating machine oil taken out together with the discharged refrigerant is given a centrifugal force by the retainer 21 accommodated in the oil separator 16, and the retainer 21 and The refrigerating machine oil collides with the peripheral wall of the oil separator 16, and the refrigerating machine oil is separated due to the difference in specific gravity from the discharged refrigerant, and is stored in the bottom portion of the oil separator 16. Refrigerating machine oil has no compatibility (incompatibility) with the refrigerant and has a large specific gravity, so that it has excellent oil separation performance in comparison with conventional refrigerating machine oil having excellent solubility.

On the other hand, the refrigerating machine oil accumulated in the lower part of the oil separator 16 is returned to the compressor 11 from the suction side of the compressor 11 through the oil return line 18. Therefore, by installing the oil separator 16 and returning the refrigerating machine oil recovered by the oil separator 16 to the compressor 11, the refrigerating machine oil does not circulate in the refrigeration cycle 10 and is quickly recovered by the compressor 11. Therefore, oil shortage in the compressor 11 can be reliably and effectively prevented.

When the refrigeration cycle 10 is stopped for a long period of time, the refrigerating machine oil and the liquid refrigerant stored in the compressor 11 are separated and stored in two layers due to the difference in specific gravity. However, the refrigerating machine oil, which has a larger specific gravity than the liquid refrigerant, is stored in the lower layer, so that the compressor
Even when 1 is restarted, the refrigerating machine oil on the lower layer side is smoothly guided to the compressor lubrication portion by the oil pump (not shown) attached to the motor output shaft. Therefore,
Does not impair lubrication performance when the compressor is restarted.

Furthermore, when epoxy-modified silicone oil is selected as the refrigerating machine oil, the epoxy ring reacts with hydrofluoric acid to form a stable compound, so that the adverse effect caused by hydrofluoric acid can be prevented. When the refrigeration cycle 10 using the HFC refrigerant is operated for a long time, a part of the HFC refrigerant is chemically decomposed to generate hydrofluoric acid. When hydrofluoric acid is generated, the enamel of the motor winding (magnet wire) in the compressor 11 reacts with hydrofluoric acid to deteriorate the insulation performance, or foreign matter is accumulated in the capillary tube 13 as an expansion mechanism to expand (decompress). ) It has various adverse effects such as deterioration of performance.

However, when the epoxy modified silicone oil is selected and used as the refrigerating machine oil, the HFC refrigerant is decomposed and hydrofluoric acid is generated by operating the refrigeration cycle 10 using the HFC refrigerant or the HFC mixed refrigerant for a long time. However, as shown in FIG. 4, since the epoxy ring reacts with hydrofluoric acid to form a stable compound, it is possible to reliably prevent deterioration of the insulation performance of the motor winding and the performance of the expansion mechanism.

[0037]

As described above, in the refrigeration cycle according to the present invention, the environment-friendly HFC refrigerant or HFC mixed refrigerant is used as the compressor refrigerant, and the compressor lubricating oil is incompatible with the refrigerant. Since refrigerating machine oil with a larger specific gravity than the refrigerant is used, it is possible to prevent the refrigerant from dissolving in the refrigerating machine oil in advance, prevent the oil viscosity from decreasing due to dilution, improve the oil sealability and compressor performance, and improve wear. It is possible to provide a highly reliable refrigeration cycle by preventing seizure and seizure.

Further, since the refrigerator is kept incompatible with the refrigerant, it is possible to prevent the refrigerator oil from being diluted, maintain the oil viscosity, and improve the lubricating performance.

Further, since the refrigerating machine oil employs a compressor lubricating oil which is incompatible with the refrigerant, it is possible to effectively prevent the refrigerating machine oil from being dissolved in the discharged refrigerant and taken out to the refrigeration cycle, and the oil level in the compressor is reduced. It is possible to prevent the oil from running out and prevent the oil from running out. When an oil separator is provided in the refrigeration cycle, a very small amount of refrigerating machine oil taken out together with the discharged refrigerant from the compressor can be separated and recovered by this oil separator. By guiding the separated and collected refrigerating machine oil to the compressor suction side, the oil level in the compressor is further stabilized, and the lubricating function of the compressor can be sufficiently maintained for a long period of time.

Furthermore, the refrigerating machine oil is HFC refrigeration or HF.
Since it is incompatible with C-mixed refrigerant and has a higher specific gravity than liquid refrigerant such as HFC refrigerant, refrigerating machine oil can be smoothly guided to the compressor lubrication part by the oil pump when the compressor is restarted, and seizure of the compressor And damage can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a cycle diagram showing an embodiment of a refrigeration cycle according to the present invention.

FIG. 2 is a sectional view of an oil separator incorporated in the refrigeration cycle of FIG.

FIG. 3 is a diagram showing a refrigerant and a refrigerating machine oil used in the refrigerating cycle of the present invention, respectively.

FIG. 4 is a diagram showing a reaction formula when an epoxy-modified silicone oil is selected as a refrigerator oil.

[Explanation of symbols]

 10 Refrigeration Cycle 11 Compressor 12 Condenser 14 Expansion Mechanism 15 Evaporator 16 Oil Separator 17 Accumulator 18 Oil Return Line 20 Sealed Case 21 Retainer

Claims (4)

[Claims] 1. In a refrigeration cycle equipped with a compressor, an HFC refrigerant or a mixed refrigerant thereof is adopted as a refrigerant for a compressor, and a refrigerating machine oil which is incompatible with this refrigerant and has a larger specific gravity than the liquid refrigerant is used as a lubricating oil for a compressor. A refrigeration cycle characterized by that. 2. The refrigeration cycle according to claim 1, wherein an oil separator is provided in the refrigeration cycle to separate refrigerating machine oil from the compressor refrigerant. 3. A refrigerating machine oil comprising polyphenyl ether, silicone oil, tricresyl phosphate, triphenyl phosphate, dimethyl phthalate, chlorofluorocarbon or perfluoroalkyl polyether, or an oil mixture thereof. Refrigeration cycle. 4. The refrigerating cycle according to claim 1, wherein a solid lubricating additive such as molybdenum disulfide, tungsten disulfide, graphite fluoride and polytetrafluoroethylene is added to the refrigerating machine oil.